Rotation of polarization axis of injection lasers with viewing direction

It is shown theoretically that in lasers with box modes and polarization determined by facet reflectivity, the axis of polarization rotates with viewing direction. For thin double-heterojunction (DHJ) cavities, the angle ρ between the junction plane and the
E
field of the radiation depends on the angles θ and φ in the junction plane and transverse to it,
\rho \approx 10^{-2}\theta\phi
in degrees. It is suggested that this behavior is a useful test for control of polarization by facet reflection. Measurements show the relation is followed in wide sawed lasers with good box modes prepared from a thin DHJ wafer and in a narrow stripe laser from the same wafer. A second narrow stripe laser from the wafer and a single-heterojunction (SHJ) cavity have no such dependence. Qualitative discussion of the measurements reveals information about polarization and mode properties not previously available.